(N/A) To classify a specimen,we observe its fundamental biological features. The following steps are used for classification:
$(i)$ Level of organization: Determine if it is at the $\text{cellular}$,$\text{tissue}$,or $\text{organ}$ level.
$(ii)$ Body symmetry: Check if the organism exhibits $\text{radial}$ or $\text{bilateral}$ symmetry.
$(iii)$ Germ layers: Identify if it is $\text{diploblastic}$ or $\text{triploblastic}$.
$(iv)$ Body cavity (Coelom): Determine if the coelom is $\text{absent}$ $(\text{acoelomate})$,$\text{pseudocoelomate}$,or a $\text{true coelom}$ $(\text{eucoelomate})$.
$(v)$ Segmentation: Check for the presence or absence of $\text{metameric segmentation}$.
$(vi)$ Notochord: Check for the presence or absence of a $\text{notochord}$ to distinguish between $\text{non-chordates}$ and $\text{chordates}$.
By systematically evaluating these features,one can classify the specimen into its respective phylum.